Chromium plated article



Dec. 8, 1931. c. VAN DERAU CHROMIUM PLATED ARTICLE Filed Jan. 5, 1929 NV E N TO R zrzzce %17 171 12- ATTORNEY Patented Dec. 8, 1931 UNITEDSTATES 'PATENT, "OFFICE CLARENCE VAN DEEAU, OF MANSFIELD, OHIO, ASSIGNOR1'0 WESTINGHOUSE ELECTRIC &; MANUFACTURING- GOIMIPAITY,- A. CORPORATIONOF PENNEY VANIA mom rm'rnn Application filed January'fi, 1929.Serial-Ho. 830,505.

My invention relates to' chromium-plated articles and more particularlyto articles of this type having a foundation metal which magnbe easilycast into any desired form.

5 object of my invention is to provide a chromium-plated article havinga foundation metal comprising lead or tin, or an alloy containing thesemetals, and a small amount of another metal,'such as antimony, in such.

proportions that the alloy may be cast into solid or tubular form.

Another object of m invention is to provide an article of manu acturehaving a foundation metal formed of an alloy, containing lead, tin andantimony, u on which is plated succe ssive layers of ca 'um, nickel andchromium. A further object of my invention is to provide a method ofplating a'foundation metal,

containing a soft metalor alloy, with a protective layer of chromium,which comprises polishing the foundation metal, coating it with a metalthat has a temperature coefiicient of expansion similar to thefoundation metal, electrode ositin'g a layer of nickel on the coatedfoun ation metal to provide'a lustrous surface, and fi ially depositingan outer layer of chromium.

In plating comparatively soft metals with chromium, such as copper orbrass, it is customary to polish the foundation metal and to coat itwith a layer of nickel before the No. 76,119, filed and assigned to theWestinghouse Electric & Manufacturing Company.

In applying this method to a foundation metal composed of alloyscontaining either lead or tin, or both of these metals in combinationwith a small percentage of other metals, suchas copper or antimony, itwas found that the nickel would not adhere to the foundation'metalduring the subsequent chro-. mlum-plating operation.

In the bath utilized in the electrodeposition of chromium, which ismaintained at a temperature of approximately 135 F. during the platingprocess, there'is a considera-- ble' evolution of gas which is causedprinci- 6o pally by the decomposition of water. Nick e1 has a lineartemperature coeflicient of expansion much less than that of tin or lead,or an alloy' containing these two metals, and it is believed that thescaling of the nickel coating during-the chromium-plating process iscaused by the foundation metal expanding, under the influence of heat,to a greater extent than the nickelcoating. Undoubtedly, the evolutionof gas alsohas the tendency 70 to preventan even deposition of chromium.

-I have made the discovery that'chromium can be successfully platedu'pon foundation metals containing lead, 131111.01 alloys of suchmetals, with a small percentage of antimony or copper, by firstelectrodepositing a layer of cadmium on-the foundation metal beforeapplying the layer of nickel.

My method is particularly adapted in producing a good adherent layer ofchromium on a foundation metal composed of an allo containingapproximately to lea 29% to 39% tin and about 1% of antimony. It mayalso be applied with good results to a foundation metal composed of leador tin alone, or to those alloys which are known in the art as Britanniametals and which are usually composed of tin, copper and antimony,although small proportions of zinc, lead and bismuth may be present.Such alloys are characterized by the fact that they may be easily castinto any desired form without shrinking, and any decorative emblems thatare formed in the molds will be accurately reproduced on the moldedmetal. My invention will be better understood by reference to theaccompanying drawings,

. in which,

Figure 1 is a side elevational view of a chromium-plated handle of apercolator having a foundation metal composed of a Britannia metal.

Fig. 2 is a similar view of the spout of a percolator having afoundation metal composed of the same alloy.

3 is a cross sectional view, on an enlargel scale, taken on the lineIIII of Fig. 2 an Fig. 4. is a similar View, taken on the line 20 IVIVof Fig. 2.

In practicing my invention, the foundation metal is cast in a solid orin a tubular form, as shown in the drawings. It is then polished and alayer of cadmium is applied by an electroplating process. A layer ofnickel is next deposited, which provides a smooth lustrous coating uponwhich the outer layer of chromium is plated.

I have found that, when the cadmium is adherent coating of-chromium willbe produced. The coefficients of expansion per degree Fahrenheit oflead, tin and cadmium are .2940x10- .2257 10- and .3159 10-*,respectively, while that of nickel is .1397 X 10- 2- It will be notedthat cadmium has a coefficient of expansion much more nearly like thatof lead and tin than nickel. It is believed that this is the reason whycadmium will adhere to the foundation metal better than nickel. Nodifliculty, however, is encountered in producing an adherent layer ofnickel upon the cadmium, even though their temperature coeflicients oflinear expansion are considerably different.

The nickel serves as a backing for the chromium and provides a smoothsurface upon which it may be plated. It has almost the same color andreflectivity as chromium and is especially desirable in the event thatthe chromium becomes thin or worn through.

While I have described a preferred embodiment of my invention, it willbe understood that various modifications may be made therein withoutdeparting from the spirit of my invention. For example, if desired, thechromium may be deposited directly on the layer of cadmium. I prefer,however, to'utilize an intermediate coatingof nickel.

Other modifications of my invention will be apparent to those skilled inthe art and I desire, therefore, that only such limitations shall beimposed thereon as are required by 65 the prior art-and the appendedclaims. I

first applied to the foundation metal, a more sesame I claim as myinvention:

1. A chromium-plated article having a foundation metal comprising analloy containing tin, an electrodeposited layer of cadmium on thefoundation metal, an outer layer of chromium, and a layer of nickelinterposed between the layer of cadmium and taining lead, tin andantimony, an electrodeposited layer of cadmium on the foundation metal,an outer layer of chromium, and a layer of nickel interposed between thelayer of cadmium and the layer of chromium. I

4:. A chromium-plated article having a foundation metal comprising analloy containing 60% to 70% lead, 29% to 39% tin and about 1% antimony,and successive layers of cadmium, nickel and chromium upon the foundtionmetal.

5. The method of producing a chromiumplated article having a foundationmetal of an alloy containing tin which comprises casting the foundationmetal into any desired form, electrodepositing a layer of cadmium uponthe cast foundation metal and then electrodepositing a layer of chromiumupon the cadmium surface.

6. The method of producing a chromiumplated article having a foundationmetal of an alloy containing tin, lead and antimony which comprisescasting the foundation metal into any desired form and electrodepositingsuccessive layers of cadmium, nickel and chromium upon the castfoundation metal.

7 The method of producing a chromiumplated article which comprisescastin Britannia metal in any desired form, polishing its surface andelectrodepositing thereon successive layers of cadmium, nickel and 1chromium.

8. The method of producing a chromiumplated article which comprisescasting a foundation metal composed of an alloy containing tin andantimony, plating the foundation metal with an intermediate metal havinga coefiicient of expansion similar to the foundation metal and thenelectrodepositing successive layers of nickel and chromium upon theintermediate layer of metal.

9. A chromium-plated article having a foundation metal which may bereadily cast into any desired form comprising an alloy containing tin, alayer of cadmium and an outer layer of chromium.

10. A chromium-plated article having a foundation metal comprising analloy containing tin and lead which may be readil cast into any desiredform, a layer of c mium and an outer layer of chromium.

11. A chromium-plated article comprising an alloy containing tin leadand antimon which may be readily cast into any desire form, a layer ofcadmium and an outer layer of chromium.

In testimony whereof, I have hereunto subscribed my name this 4th day ofDecember, 1928.

CLARENCE VAN DERAU.

